According to the A’s official Twitter feed, left-hander Brett Anderson was diagnosed with a strained right trapezius muscle Sunday after making an early exit from his Cactus League start against the D’Backs.

Anderson collided with the Snakes’ Adam Eaton around the third base bag in the first inning. He wound up throwing only eight pitches, yielding one hit and two runs (though just one was earned).

The talented 25-year-old southpaw will probably skip his next turn in Oakland’s spring rotation but that wouldn’t necessarily rule him out for his scheduled Opening Day start — April 1 — against the Mariners.

The trapezius muscle extends down from the neck to the middle of the back. It’s on his non-throwing side, so he should be able to resume light mound work within a week or so. The A’s will reevaluate him on Monday.

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UPDATE, 5:21 PM: Anderson downplayed the injury when he spoke to reporters in the clubhouse, according to MLB.com’s Tyler Emerick. It just spazzed up on me,” said Anderson. “It’s not something I’m too worried about.” Anderson is considered day-to-day.